what is it raining

Rain is formed from water vapour in the surrounding atmosphere. Water vapour forms when the heat of the sun evaporates water from oceans and other bodies of water on earth, including plants through transpiration. The warm and moist air cools down as it rises into the atmosphere. This reduces the amount of water vapour that the atmosphere can hold. The temperature at which air can hold the most amount of water vapour is called the Dew Point. When the temperature drops below the dew point, some of the water vapour condenses into water vapour, forming clouds. Water droplets form on tiny particles called condensation nuclei, which are made up of dust, salt from ocean spray and chemicals given off by industrial plants and vehicles. During the formation of water vapour, heat is liberated, warming the clouds. This allows the clouds to rise higher and eventually become cooler again. The formation of raindrops is explained by the coalescence theory and the ice-crystal theory.